Predation marks on snail shells

This research is about an ichnofossil, also called a “trace fossil”. Trace fossils are records of biological activity and may be impressions made on the substrate by an organism (burrows, footprints etc.), feeding marks (bites, holes etc.) or any vestige a living being might leave behind.

nihilichnus-covichi
Holes (predation marks) left on shells of the freshwater snail Nematurella bavarica. The arrows show incomplete holes.

We have found curious holes on the shells of freshwater gastropods from the Miocene of southern Germany and wondered what could have caused them. The holes are always on the same place on the shell, so we could discard the possibility they were artifacts from the fossilization process. They all looked too regular and consistent, so we suspected they were the work of a predator. After carefully considering our possibilities (which predator are known from the same fossil outcrops as our snails), we reached the conclusion that these predation marks were made by a fish, namely a tench (Tinca sp.).

Ichnofossils may be described and named as regular species, with a double Latin name and all. This is done in order to facilitate communication between researchers, so by giving it a name, anyone can know what trace fossil you are talking about. We thus described this new kind of trace fossil as Nihilichnus covichi, in honor of Alan P. Covich, who first documented it.


Bibliography

The preceding text is a summary of the following paper, where this research was published: RASSER, M.W.; VALLON, L.H.; SALVADOR, R.B. 2016. Perforations of Freshwater Snail Shells from the Miocene of Germany: Nihilichnus covichi n. isp. Ichnos 23(3–4): 222–227.  [PDF]

The first paper on these predation marks is: Rasser, M.W. & Covich, A. 2014. Predation on freshwater snails in Miocene Lake Steinheim: a trigger for intralacustrine evolution? Lethaia 47(4): 524-532.  [LINK]